From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4CF4C10F12 for ; Wed, 17 Apr 2019 08:39:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A12F721773 for ; Wed, 17 Apr 2019 08:39:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731379AbfDQIj5 (ORCPT ); Wed, 17 Apr 2019 04:39:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36846 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726895AbfDQIj4 (ORCPT ); Wed, 17 Apr 2019 04:39:56 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E58DE59464; Wed, 17 Apr 2019 08:39:55 +0000 (UTC) Received: from localhost (ovpn-12-202.pek2.redhat.com [10.72.12.202]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0E71C5D9D5; Wed, 17 Apr 2019 08:39:54 +0000 (UTC) Date: Wed, 17 Apr 2019 16:39:52 +0800 From: Baoquan He To: Borislav Petkov Cc: kirill@shutemov.name, linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com, keescook@chromium.org, peterz@infradead.org, thgarnie@google.com, herbert@gondor.apana.org.au, mike.travis@hpe.com, frank.ramsay@hpe.com, yamada.masahiro@socionext.com Subject: Re: [PATCH v2 RESEND 2/2] x86/mm/KASLR: Fix the size of vmemmap section Message-ID: <20190417083952.GA23459@localhost> References: <20190414072804.12560-1-bhe@redhat.com> <20190414072804.12560-3-bhe@redhat.com> <20190415194755.GJ29317@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190415194755.GJ29317@zn.tnic> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 17 Apr 2019 08:39:56 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/15/19 at 09:47pm, Borislav Petkov wrote: > On Sun, Apr 14, 2019 at 03:28:04PM +0800, Baoquan He wrote: > > kernel_randomize_memory() hardcodes the size of vmemmap section as 1 TB, > > to support the maximum amount of system RAM in 4-level paging mode, 64 TB. > > > > However, 1 TB is not enough for vmemmap in 5-level paging mode. Assuming > > the size of struct page is 64 Bytes, to support 4 PB system RAM in 5-level, > > 64 TB of vmemmap area is needed. The wrong hardcoding may cause vmemmap > > stamping into the following cpu_entry_area section, if KASLR puts vmemmap > > very close to cpu_entry_area, and the actual area of vmemmap is much bigger > > than 1 TB. > > > > So here calculate the actual size of vmemmap region, then align up to 1 TB > > boundary. In 4-level it's always 1 TB. In 5-level it's adjusted on demand. > > The current code reserves 0.5 PB for vmemmap in 5-level. In this new methor, > ^^^^^^^ > > Please introduce a spellchecker into your patch creation workflow. Sorry, forgot running checkpatch this time. Will update. > > > the left space can be saved to join randomization to increase the entropy. > > > > Signed-off-by: Baoquan He > > --- > > arch/x86/mm/kaslr.c | 11 ++++++++++- > > 1 file changed, 10 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c > > index 387d4ed25d7c..4679a0075048 100644 > > --- a/arch/x86/mm/kaslr.c > > +++ b/arch/x86/mm/kaslr.c > > @@ -52,7 +52,7 @@ static __initdata struct kaslr_memory_region { > > } kaslr_regions[] = { > > { &page_offset_base, 0 }, > > { &vmalloc_base, 0 }, > > - { &vmemmap_base, 1 }, > > + { &vmemmap_base, 0 }, > > }; > > > > /* Get size in bytes used by the memory region */ > > @@ -78,6 +78,7 @@ void __init kernel_randomize_memory(void) > > unsigned long rand, memory_tb; > > struct rnd_state rand_state; > > unsigned long remain_entropy; > > + unsigned long vmemmap_size; > > > > vaddr_start = pgtable_l5_enabled() ? __PAGE_OFFSET_BASE_L5 : __PAGE_OFFSET_BASE_L4; > > vaddr = vaddr_start; > > @@ -109,6 +110,14 @@ void __init kernel_randomize_memory(void) > > if (memory_tb < kaslr_regions[0].size_tb) > > kaslr_regions[0].size_tb = memory_tb; > > > > + /** > > + * Calculate how many TB vmemmap region needs, and aligned to > > + * 1TB boundary. > > + */ > > + vmemmap_size = (kaslr_regions[0].size_tb << (TB_SHIFT - PAGE_SHIFT)) * > > + sizeof(struct page); > > + kaslr_regions[2].size_tb = DIV_ROUND_UP(vmemmap_size, 1UL << TB_SHIFT); > > + > > /* Calculate entropy available between regions */ > > remain_entropy = vaddr_end - vaddr_start; > > for (i = 0; i < ARRAY_SIZE(kaslr_regions); i++) > > -- > > Kirill, ack? > > -- > Regards/Gruss, > Boris. > > Good mailing practices for 400: avoid top-posting and trim the reply.